14 CFR 47.40: Registration expiration and renewal.

(a) Initial Registration. A Certificate of Aircraft Registration issued in accordance with § 47.31 expires seven years after the last day of the month in which it is issued.

(b) Renewal. Each holder of a Certificate of Aircraft Registration containing an expiration date may apply for renewal of a Certificate of Aircraft Registration by submitting an Aircraft Registration Renewal Application, AC Form 8050-1B, and the fee required by § 47.17 during the six months preceding the expiration date for the Certificate of Aircraft Registration.

(c) Inaccurate Information. The Administrator may require the owner of a registered aircraft to submit a complete Aircraft Registration Application, AC Form 8050-1, and fee prior to the expiration date if the Administrator finds that the Certificate of Aircraft Registration contains inaccurate information.